The consequence of subduction at oceanic-continental plate boundaries is primarily:
3) Creation of island arcs and ocean trenches
At these boundaries, the denser oceanic plate subducts beneath the lighter continental plate, leading to the formation of ocean trenches and volcanic arcs. While the correct answer involves the creation of ocean trenches, it's important to note that island arcs typically form at oceanic-oceanic boundaries rather than oceanic-continental. However, the presence of volcanic activity due to subduction is relevant to the process at oceanic-continental boundaries.